Electronic safety device and a conveyor system

Abstract

The invention relates to an electronic safety device and a conveyor system comprising the same. The electronic safety device has a safety input for receiving a safety signal, the electronic safety device being configured to terminate its operation responsive to absence of the safety signal in the safety input. The electronic safety device comprises an operation-preventing circuit configured to detect an operational anomaly in the safety input, the operation-preventing circuit comprising a switch adapted to short the safety input when the operational anomaly is present in the safety input.

The invention claimed is: 
     
       1. An electronic safety device comprising:
 a safety input terminal configured to receive a safety signal, the electronic safety device configured to block operation of an elevator, if the safety signal is not detected at the safety input terminal; and 
 an operation-preventing device configured to detect an operational anomaly in the safety input terminal, the operation-preventing circuit including a switch configured to short the safety input terminal, if the operational anomaly is detected in the safety input terminal. 
 
     
     
       2. The electronic safety device according to  claim 1 , wherein the operational anomaly includes a presence of an unallowed voltage applied to the safety input terminal. 
     
     
       3. The electronic safety device according to  claim 2 , wherein the operation-preventing circuit is configured to detect the unallowed voltage by momentarily shorting the safety input terminal. 
     
     
       4. The electronic safety device according to  claim 3 , wherein the operation-preventing circuit is configured to detect the unallowed voltage by momentarily shorting the safety input terminal during a power-up situation of the electronic safety device. 
     
     
       5. The electronic safety device according to  claim 1 , wherein the switch is configured to short the safety input terminal until the operational anomaly is cleared from the safety input terminal. 
     
     
       6. The electronic safety device according to  claim 1 , wherein the switch is configured to short the safety input terminal, if an overvoltage is detected at the safety input terminal. 
     
     
       7. The electronic safety device according to  claim 1 , wherein the operation-preventing circuit further comprises:
 a power supply having an output terminal coupled to a control pole of the switch. 
 
     
     
       8. The electronic safety device according to  claim 1 , wherein the switch is a thyristor. 
     
     
       9. The electronic safety device according to  claim 1 , wherein the electronic safety device is configured to operate, if the safety signal is present at the safety input terminal. 
     
     
       10. The electronic safety device according to  claim 1 , wherein the electronic safety device is a control device of an electromagnetic brake. 
     
     
       11. The electronic safety device according to  claim 1 , wherein the electronic safety device is a conveyor driver. 
     
     
       12. A conveyor system comprising:
 a safety system configured to output the safety signal; and 
 the electronic safety device according to  claim 1 , the safety input terminal of the electronic safety device configured to receive the safety signal output from the safety system. 
 
     
     
       13. An electronic safety device configured to control an elevator system, the electronic safety system configured to connect to a controller configured to engage one or more safety devices by selectively disconnecting a safety signal from a safety input terminal associated with the one or more safety devices based on safety data generated by one or more safety contacts, the electronic safety device comprising:
 an operation preventing device connected to the safety input terminal, the operation preventing device including a switch, the operation preventing device configured to engage the one or more safety devices by adjusting the switch to short the safety input terminal, if the operation preventing device detects an anomaly present at the safety input terminal. 
 
     
     
       14. The electronic safety device of  claim 13 , wherein the controller is configured to disconnect the safety signal from the safety input terminal, if the safety data indicates an abnormal elevator operation. 
     
     
       15. The electronic safety device of  claim 14 , wherein the abnormal elevator operation is a state in which one or more of the safety contacts are set to an open position. 
     
     
       16. The electronic safety device of  claim 15 , wherein the one or more safety contacts are set to the open position when an entrance to an elevator hoistway is open and an overspeed governor is activated. 
     
     
       17. The electronic safety device of  claim 13 , wherein the anomaly at the safety input terminal includes one or more of the safety signal having an abnormal voltage level based on a current state of the elevator system and an overload voltage present at the safety input terminal. 
     
     
       18. The electronic safety device according to  claim 13 , wherein the switch is configured to short the safety input terminal until the anomaly is cleared from the safety input terminal. 
     
     
       19. The electronic safety device of  claim 13 , wherein the switch is a thyristor having an anode, a gate, and a cathode, the cathode configured to receive a reference voltage, and the thyristor configured to selectively supply the reference voltage to the anode to short the safety input terminal based on a gate voltage applied to the gate.